Technical Abstract:
Streptococcus iniae is the Gram-positive bacteria that cause of significant economic losses in aquaculture production of a number of cultured fish species, worldwide. A health management practice that has most recently emerged is the prevention of S. iniae infection by vaccination. Previously, limited research and development of safe and effective vaccines against fish pathogens had been done and was limited to the development of autogenous type vaccines for a particular aquaculture production site. Research has indicated that best protection of killed bacterin-type vaccine is by injection administration. In Israel, streptococcal vaccines are said to increase profits by 12 dollars for every dollar spent. This type of return suggests that injection vaccination is economically feasible. Our research has led to the development of an injectable bacterin-toxoid vaccine that is highly effective in preventing S. iniae infection in tilapia and hybrid striped bass. The vaccine is safe, effective without adjuvant and provides at least a 3-month duration of protection in tilapia against S. iniae. This review will discuss the advantages of vaccination against streptococcal disease, update the current status of research and development, and the need to involve vaccine and aquaculture industries as well as governmental regulatory agencies to enhance fish vaccine use as a management practice for the control of fish pathogens.